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The US and EU have reached agreement on a compatibility plan for location signals to be transmitted by new American and European navigation satellites.

In a joint press release today, US and EU authorities announced a signal plan to be implemented on the future European Galileo Open Service and the American GPS IIIA new civil signal.

In a widely-anticipated move, the forthcoming sat-nav transmissions will use a waveform known as Multiplexed Binary Offset Carrier, or MBOC.

The European and American negotiators said: "Future receivers using the MBOC signal should be able to track the GPS and/or Galileo signals with higher accuracy in challenging environments that include multipath, noise, and interference... Future civilian users will enjoy the benefits of multiple constellations providing greater signal availability and coverage around the world."

During the past couple of years, there has been some debate as to the way ahead in sat-nav technology, with different groups seeing different priorities. In essence, one lobby has wanted to see a sat-nav signal optimised for use by cheaper user receiving equipment; another group has advocated greater performance and precision.

MBOC is generally seen as favoured by the latter group, providing potentially greater performance at the cost of more complex user equipment.

According to this abstract of a paper delivered at a sat nav conference in Switzerland two months ago:

"The final touch to the Galileo signal plan was achieved when the Working group on GPS and Galileo compatibility... finally concluded on the great interest of a new modulation... namely MBOC. This was pursuant to efforts mainly driven by the European side but fully recognised by the US representatives... After many years of intensive work on the European side, the final Galileo Signal Plan is presented and analysed."

Both American and European members of the governmental working group have reportedly been highly enthusiastic about MBOC and its advantages.

Nonetheless, MBOC has its detractors. There are those who would have preferred simpler, non-multiplexed binary offset carrier (BOC) tech to be used.

For instance, Qualcomm manufactures chipsets which are used to integrate sat nav functions into mobile phones. The company last year told the magazine GPS World:

"[MBOC] modulation will penalise all devices that do not employ a wideband receiver, that is, most consumer devices and GPS-enabled wireless phones... reducing the devices' ability to operate in highly blocked environments. Granted this performance is better than using the legacy signal, but it is worse than what would be achievable using the originally proposed BOC modulation.

"This will result in performance degradation to the vast majority of GPS-enabled consumer devices... relative to what would otherwise be achievable."

Nothing will get worse for ordinary sat nav users, then, but if Qualcomm is right they won't see much of an improvement either as American GPS Block III and European Galileo spacecraft come online.

That might be a little unfair, as GPS has always been paid for by the ordinary US taxpayer, and it now seems certain that Galileo will be paid for by the ordinary European taxpayer. Both systems will now have their open signals optimised towards professional, specialist users - if you accept the Qualcomm assessment, anyway.

According to the joint US-EU announcement, the agreement will bring in "interoperable optimised civil signals that will also protect common security interests". ®